package fzf

import (
	"fmt"
	"os"
	"regexp"
	"strings"
	"unicode/utf8"

	"github.com/junegunn/fzf/src/curses"

	"github.com/junegunn/go-shellwords"
)

const usage = `usage: fzf [options]

  Search mode
    -x, --extended        Extended-search mode
    -e, --extended-exact  Extended-search mode (exact match)
    -i                    Case-insensitive match (default: smart-case match)
    +i                    Case-sensitive match
    -n, --nth=N[,..]      Comma-separated list of field index expressions
                          for limiting search scope. Each can be a non-zero
                          integer or a range expression ([BEGIN]..[END])
        --with-nth=N[,..] Transform the item using index expressions for search
    -d, --delimiter=STR   Field delimiter regex for --nth (default: AWK-style)

  Search result
    +s, --no-sort         Do not sort the result
        --tac             Reverse the order of the input
        --tiebreak=CRI    Sort criterion when the scores are tied;
                          [length|begin|end|index] (default: length)

  Interface
    -m, --multi           Enable multi-select with tab/shift-tab
        --ansi            Enable processing of ANSI color codes
        --no-mouse        Disable mouse
        --color=COL       Color scheme; [dark|light|16|bw]
                          (default: dark on 256-color terminal, otherwise 16)
        --black           Use black background
        --reverse         Reverse orientation
        --no-hscroll      Disable horizontal scroll
        --inline-info     Display finder info inline with the query
        --prompt=STR      Input prompt (default: '> ')

  Scripting
    -q, --query=STR       Start the finder with the given query
    -1, --select-1        Automatically select the only match
    -0, --exit-0          Exit immediately when there's no match
    -f, --filter=STR      Filter mode. Do not start interactive finder.
        --print-query     Print query as the first line
        --expect=KEYS     Comma-separated list of keys to complete fzf
        --toggle-sort=KEY Key to toggle sort
        --bind=KEYBINDS   Custom key bindings. Refer to the man page.
        --sync            Synchronous search for multi-staged filtering

  Environment variables
    FZF_DEFAULT_COMMAND   Default command to use when input is tty
    FZF_DEFAULT_OPTS      Defaults options. (e.g. '-x -m')

`

// Mode denotes the current search mode
type Mode int

// Search modes
const (
	ModeFuzzy Mode = iota
	ModeExtended
	ModeExtendedExact
)

// Case denotes case-sensitivity of search
type Case int

// Case-sensitivities
const (
	CaseSmart Case = iota
	CaseIgnore
	CaseRespect
)

// Sort criteria
type tiebreak int

const (
	byLength tiebreak = iota
	byBegin
	byEnd
	byIndex
)

// Options stores the values of command-line options
type Options struct {
	Mode       Mode
	Case       Case
	Nth        []Range
	WithNth    []Range
	Delimiter  *regexp.Regexp
	Sort       int
	Tac        bool
	Tiebreak   tiebreak
	Multi      bool
	Ansi       bool
	Mouse      bool
	Theme      *curses.ColorTheme
	Black      bool
	Reverse    bool
	Hscroll    bool
	InlineInfo bool
	Prompt     string
	Query      string
	Select1    bool
	Exit0      bool
	Filter     *string
	ToggleSort bool
	Expect     []int
	Keymap     map[int]actionType
	PrintQuery bool
	Sync       bool
	Version    bool
}

func defaultOptions() *Options {
	var defaultTheme *curses.ColorTheme
	if strings.Contains(os.Getenv("TERM"), "256") {
		defaultTheme = curses.Dark256
	} else {
		defaultTheme = curses.Default16
	}

	return &Options{
		Mode:       ModeFuzzy,
		Case:       CaseSmart,
		Nth:        make([]Range, 0),
		WithNth:    make([]Range, 0),
		Delimiter:  nil,
		Sort:       1000,
		Tac:        false,
		Tiebreak:   byLength,
		Multi:      false,
		Ansi:       false,
		Mouse:      true,
		Theme:      defaultTheme,
		Black:      false,
		Reverse:    false,
		Hscroll:    true,
		InlineInfo: false,
		Prompt:     "> ",
		Query:      "",
		Select1:    false,
		Exit0:      false,
		Filter:     nil,
		ToggleSort: false,
		Expect:     []int{},
		Keymap:     defaultKeymap(),
		PrintQuery: false,
		Sync:       false,
		Version:    false}
}

func help(ok int) {
	os.Stderr.WriteString(usage)
	os.Exit(ok)
}

func errorExit(msg string) {
	os.Stderr.WriteString(msg + "\n")
	help(1)
}

func optString(arg string, prefix string) (bool, string) {
	rx, _ := regexp.Compile(fmt.Sprintf("^(?:%s)(.*)$", prefix))
	matches := rx.FindStringSubmatch(arg)
	if len(matches) > 1 {
		return true, matches[1]
	}
	return false, ""
}

func nextString(args []string, i *int, message string) string {
	if len(args) > *i+1 {
		*i++
	} else {
		errorExit(message)
	}
	return args[*i]
}

func optionalNumeric(args []string, i *int) int {
	if len(args) > *i+1 {
		if strings.IndexAny(args[*i+1], "0123456789") == 0 {
			*i++
		}
	}
	return 1 // Don't care
}

func splitNth(str string) []Range {
	if match, _ := regexp.MatchString("^[0-9,-.]+$", str); !match {
		errorExit("invalid format: " + str)
	}

	tokens := strings.Split(str, ",")
	ranges := make([]Range, len(tokens))
	for idx, s := range tokens {
		r, ok := ParseRange(&s)
		if !ok {
			errorExit("invalid format: " + str)
		}
		ranges[idx] = r
	}
	return ranges
}

func delimiterRegexp(str string) *regexp.Regexp {
	rx, e := regexp.Compile(str)
	if e != nil {
		str = regexp.QuoteMeta(str)
	}

	rx, e = regexp.Compile(fmt.Sprintf("(?:.*?%s)|(?:.+?$)", str))
	if e != nil {
		errorExit("invalid regular expression: " + e.Error())
	}
	return rx
}

func isAlphabet(char uint8) bool {
	return char >= 'a' && char <= 'z'
}

func parseKeyChords(str string, message string) []int {
	if len(str) == 0 {
		errorExit(message)
	}

	tokens := strings.Split(str, ",")
	if str == "," || strings.HasPrefix(str, ",,") || strings.HasSuffix(str, ",,") || strings.Index(str, ",,,") >= 0 {
		tokens = append(tokens, ",")
	}

	var chords []int
	for _, key := range tokens {
		if len(key) == 0 {
			continue // ignore
		}
		lkey := strings.ToLower(key)
		if len(key) == 6 && strings.HasPrefix(lkey, "ctrl-") && isAlphabet(lkey[5]) {
			chords = append(chords, curses.CtrlA+int(lkey[5])-'a')
		} else if len(key) == 5 && strings.HasPrefix(lkey, "alt-") && isAlphabet(lkey[4]) {
			chords = append(chords, curses.AltA+int(lkey[4])-'a')
		} else if len(key) == 2 && strings.HasPrefix(lkey, "f") && key[1] >= '1' && key[1] <= '4' {
			chords = append(chords, curses.F1+int(key[1])-'1')
		} else if utf8.RuneCountInString(key) == 1 {
			chords = append(chords, curses.AltZ+int([]rune(key)[0]))
		} else {
			errorExit("unsupported key: " + key)
		}
	}
	return chords
}

func parseTiebreak(str string) tiebreak {
	switch strings.ToLower(str) {
	case "length":
		return byLength
	case "index":
		return byIndex
	case "begin":
		return byBegin
	case "end":
		return byEnd
	default:
		errorExit("invalid sort criterion: " + str)
	}
	return byLength
}

func parseTheme(str string) *curses.ColorTheme {
	switch strings.ToLower(str) {
	case "dark":
		return curses.Dark256
	case "light":
		return curses.Light256
	case "16":
		return curses.Default16
	case "bw", "no":
		return nil
	default:
		errorExit("invalid color scheme: " + str)
	}
	return nil
}

func parseKeymap(keymap map[int]actionType, toggleSort bool, str string) (map[int]actionType, bool) {
	for _, pairStr := range strings.Split(str, ",") {
		pair := strings.Split(pairStr, ":")
		if len(pair) != 2 {
			errorExit("invalid key binding: " + pairStr)
		}
		keys := parseKeyChords(pair[0], "key name required")
		if len(keys) != 1 {
			errorExit("invalid key binding: " + pairStr)
		}
		key := keys[0]
		act := strings.ToLower(pair[1])
		switch strings.ToLower(pair[1]) {
		case "beginning-of-line":
			keymap[key] = actBeginningOfLine
		case "abort":
			keymap[key] = actAbort
		case "accept":
			keymap[key] = actAccept
		case "backward-char":
			keymap[key] = actBackwardChar
		case "backward-delete-char":
			keymap[key] = actBackwardDeleteChar
		case "backward-word":
			keymap[key] = actBackwardWord
		case "clear-screen":
			keymap[key] = actClearScreen
		case "delete-char":
			keymap[key] = actDeleteChar
		case "end-of-line":
			keymap[key] = actEndOfLine
		case "forward-char":
			keymap[key] = actForwardChar
		case "forward-word":
			keymap[key] = actForwardWord
		case "kill-line":
			keymap[key] = actKillLine
		case "kill-word":
			keymap[key] = actKillWord
		case "unix-line-discard", "line-discard":
			keymap[key] = actUnixLineDiscard
		case "unix-word-rubout", "word-rubout":
			keymap[key] = actUnixWordRubout
		case "yank":
			keymap[key] = actYank
		case "backward-kill-word":
			keymap[key] = actBackwardKillWord
		case "toggle-down":
			keymap[key] = actToggleDown
		case "toggle-up":
			keymap[key] = actToggleUp
		case "down":
			keymap[key] = actDown
		case "up":
			keymap[key] = actUp
		case "page-up":
			keymap[key] = actPageUp
		case "page-down":
			keymap[key] = actPageDown
		case "toggle-sort":
			keymap[key] = actToggleSort
			toggleSort = true
		default:
			errorExit("unknown action: " + act)
		}
	}
	return keymap, toggleSort
}

func checkToggleSort(keymap map[int]actionType, str string) map[int]actionType {
	keys := parseKeyChords(str, "key name required")
	if len(keys) != 1 {
		errorExit("multiple keys specified")
	}
	keymap[keys[0]] = actToggleSort
	return keymap
}

func parseOptions(opts *Options, allArgs []string) {
	for i := 0; i < len(allArgs); i++ {
		arg := allArgs[i]
		switch arg {
		case "-h", "--help":
			help(0)
		case "-x", "--extended":
			opts.Mode = ModeExtended
		case "-e", "--extended-exact":
			opts.Mode = ModeExtendedExact
		case "+x", "--no-extended", "+e", "--no-extended-exact":
			opts.Mode = ModeFuzzy
		case "-q", "--query":
			opts.Query = nextString(allArgs, &i, "query string required")
		case "-f", "--filter":
			filter := nextString(allArgs, &i, "query string required")
			opts.Filter = &filter
		case "--expect":
			opts.Expect = parseKeyChords(nextString(allArgs, &i, "key names required"), "key names required")
		case "--tiebreak":
			opts.Tiebreak = parseTiebreak(nextString(allArgs, &i, "sort criterion required"))
		case "--bind":
			opts.Keymap, opts.ToggleSort = parseKeymap(opts.Keymap, opts.ToggleSort, nextString(allArgs, &i, "bind expression required"))
		case "--color":
			opts.Theme = parseTheme(nextString(allArgs, &i, "color scheme name required"))
		case "--toggle-sort":
			opts.Keymap = checkToggleSort(opts.Keymap, nextString(allArgs, &i, "key name required"))
			opts.ToggleSort = true
		case "-d", "--delimiter":
			opts.Delimiter = delimiterRegexp(nextString(allArgs, &i, "delimiter required"))
		case "-n", "--nth":
			opts.Nth = splitNth(nextString(allArgs, &i, "nth expression required"))
		case "--with-nth":
			opts.WithNth = splitNth(nextString(allArgs, &i, "nth expression required"))
		case "-s", "--sort":
			opts.Sort = optionalNumeric(allArgs, &i)
		case "+s", "--no-sort":
			opts.Sort = 0
		case "--tac":
			opts.Tac = true
		case "--no-tac":
			opts.Tac = false
		case "-i":
			opts.Case = CaseIgnore
		case "+i":
			opts.Case = CaseRespect
		case "-m", "--multi":
			opts.Multi = true
		case "+m", "--no-multi":
			opts.Multi = false
		case "--ansi":
			opts.Ansi = true
		case "--no-ansi":
			opts.Ansi = false
		case "--no-mouse":
			opts.Mouse = false
		case "+c", "--no-color":
			opts.Theme = nil
		case "+2", "--no-256":
			opts.Theme = curses.Default16
		case "--black":
			opts.Black = true
		case "--no-black":
			opts.Black = false
		case "--reverse":
			opts.Reverse = true
		case "--no-reverse":
			opts.Reverse = false
		case "--hscroll":
			opts.Hscroll = true
		case "--no-hscroll":
			opts.Hscroll = false
		case "--inline-info":
			opts.InlineInfo = true
		case "--no-inline-info":
			opts.InlineInfo = false
		case "-1", "--select-1":
			opts.Select1 = true
		case "+1", "--no-select-1":
			opts.Select1 = false
		case "-0", "--exit-0":
			opts.Exit0 = true
		case "+0", "--no-exit-0":
			opts.Exit0 = false
		case "--print-query":
			opts.PrintQuery = true
		case "--no-print-query":
			opts.PrintQuery = false
		case "--prompt":
			opts.Prompt = nextString(allArgs, &i, "prompt string required")
		case "--sync":
			opts.Sync = true
		case "--no-sync":
			opts.Sync = false
		case "--async":
			opts.Sync = false
		case "--version":
			opts.Version = true
		default:
			if match, value := optString(arg, "-q|--query="); match {
				opts.Query = value
			} else if match, value := optString(arg, "-f|--filter="); match {
				opts.Filter = &value
			} else if match, value := optString(arg, "-d|--delimiter="); match {
				opts.Delimiter = delimiterRegexp(value)
			} else if match, value := optString(arg, "--prompt="); match {
				opts.Prompt = value
			} else if match, value := optString(arg, "-n|--nth="); match {
				opts.Nth = splitNth(value)
			} else if match, value := optString(arg, "--with-nth="); match {
				opts.WithNth = splitNth(value)
			} else if match, _ := optString(arg, "-s|--sort="); match {
				opts.Sort = 1 // Don't care
			} else if match, value := optString(arg, "--toggle-sort="); match {
				opts.Keymap = checkToggleSort(opts.Keymap, value)
				opts.ToggleSort = true
			} else if match, value := optString(arg, "--expect="); match {
				opts.Expect = parseKeyChords(value, "key names required")
			} else if match, value := optString(arg, "--tiebreak="); match {
				opts.Tiebreak = parseTiebreak(value)
			} else if match, value := optString(arg, "--color="); match {
				opts.Theme = parseTheme(value)
			} else if match, value := optString(arg, "--bind="); match {
				opts.Keymap, opts.ToggleSort = parseKeymap(opts.Keymap, opts.ToggleSort, value)
			} else {
				errorExit("unknown option: " + arg)
			}
		}
	}

	// If we're not using extended search mode, --nth option becomes irrelevant
	// if it contains the whole range
	if opts.Mode == ModeFuzzy || len(opts.Nth) == 1 {
		for _, r := range opts.Nth {
			if r.begin == rangeEllipsis && r.end == rangeEllipsis {
				opts.Nth = make([]Range, 0)
				return
			}
		}
	}
}

// ParseOptions parses command-line options
func ParseOptions() *Options {
	opts := defaultOptions()

	// Options from Env var
	words, _ := shellwords.Parse(os.Getenv("FZF_DEFAULT_OPTS"))
	parseOptions(opts, words)

	// Options from command-line arguments
	parseOptions(opts, os.Args[1:])
	return opts
}